Mechanical characterization of mode I fracture toughnessin multidirectional printed continuous fiber laminates.: Investigation of fracture toughness in multidirectionallaminated composites
The delamination failure mechanism between layers is one of the most critical in laminated fiber-reinforced polymer (FRP) composites, a phenomenon that has driven numerous research efforts. While a large body of literature focuses on this issue in unidirectional laminates, in-service conditions often lead to fracture initiation and propagation at interfaces with different fiber orientations. This study presents the experimental characterization of mode I fracture toughness in a continuous fiber composite manufactured through Additive Manufacturing (AM), defining configurations with multidirectional interfaces. The laminate design process for Double Cantilever Beam (DCB) specimens is detailed, ensuring stable and planar crack propagation. The proposed design methodology is validated through mechanical testing, employing laminate configurations that meet appropriate evaluation criteria. Fracture morphology of representative samples from each configuration is analyzed using Scanning Electron Microscopy (SEM), revealing similarities in surface features and specific failure mechanisms across the samples.